Bryophyte-microbe interactions and soil microbiota on the remote oceanic island of St Helena

St Helena is a British Overseas Territory in the South Atlantic Ocean, known particularly for its remoteness, standing 1950 km away from the nearest continent, Africa. The island hosts unique wildlife with a high rate of endemism, especially in its cloud forest (the Peaks National Park), which is critical for the island's water security and tourism industry.
In my PhD I aim to fill knowledge gaps identified in the Peaks National Park Conservation Management Plan to enable better informed habitat conservation policies. This includes the first ever study of the whole microbiome (prokaryotes, protists, fungi) of the soils of the cloud forest and other habitats, which will serve as baseline knowledge and will reveal factors structuring microbial communities on the island. The method being used is eDNA metabarcoding, which I also employ to study the total microbiomes of the bryophytes (mosses, liverworts, hornworts) of St Helena, and also compare them to those from soil to understand how they are linked.
This serves to provide an idea of how a functionally neglected group, the bryophytes, may be contributing vital ecosystem functions on the island in no small part via its microbiome, something the literature suggests for cloud forests. In a broader perspective, knowledge of how bryophyte microbiomes change between different types of habitat, and to what extent this differs between host species, is a major knowledge gap. Many bryophyte lineages have not had their microbiomes researched thoroughly and this work focuses on some of them.
Apart from the molecular approach, I also employ light and scanning electron microscopy to structurally characterise host-microbe interactions. In vitro culturing experiments are also being performed to understand the physiological significance of the mutualism of the least studied bryophytes -the hornworts- with endophytic cyanobacteria and mycorrhizal fungi, a tripartite association that has not been experimentally studied so far.